Architectural wall panel systems, including both metal and composite wall panel systems, have been used extensively for some time, primarily in the commercial and industrial building markets. In recent years, the popularity of composite wall panel systems, in particular, has been increasing steadily. There are a number of factors that may be credited for the wide-spread and increased use of such wall panel systems. One such factor is the high cost to construct commercial and industrial buildings, which tend to be relatively large from stone or brick. Wood is not a suitable substitute due to the large loads the buildings supporting structure must withstand. Another factor effecting the increased use of metal and composite wall panel systems is the high durability of the systems. Both the metals and composites used to make the panels for wall panel systems are highly resistant to damage from sun, dirt, moisture, fire, and many other environmental elements. Consequently, the metal and composite wall panel systems have a long life, and may require less maintenance than other alternative building materials and systems.
Architectural wall panel systems can generally be placed into one of two categories: face-sealed architectural panel systems or vented rain-screen architectural panel systems. Face-sealed architectural panel systems include those systems that have a sealant in both the horizontal and vertical joints between adjacent wall panels. The sealants make the wall panel system impermeable to air and water, and may include caulking, gaskets, or other sealants with a similar function. Vented rain-screen architectural panel systems are those systems designed to allow permeability through the joints between adjacent wall panels. The permeable joints allow for breathability and rapid pressure equalization within the wall panel system to prevent pressure buildups behind the panels.
Architectural wall panel systems have many advantages, as discussed above, however, these systems may also present a number of challenges and disadvantages. One such challenge is the thermal expansion and contraction of the wall panels. The metal and composite materials used most commonly in architectural wall panel systems are subject to natural expansion and contraction due to changes in atmospheric conditions, including heat and humidity. If a means of accommodating this inherent thermal cycling is not provided in the attachment system of the architectural wall panel system, then the panels can become warped and cracked, requiring repair work or replacement. A second challenge that may be associated with architectural wall panel systems is directly related to the first issue of thermal cycling, and relates to the effectiveness of sealants used in joints between adjacent wall panels in face-sealed architectural panel systems. Because the joints increase and decrease in size during thermal cycling, sealants often become dislodged and/or cracked and are thereafter ineffective at preventing the infiltration of air and water. As a result, sealants used in face-sealed architectural panel systems have proven disappointingly ineffective.
Another disadvantage associated with many architectural wall panel systems is the complexity of the system, including the number of pieces and parts needed and the extensive time and labor required to install the complex system. In particular, where a form of attachment clips are used to secure the wall panels to the substructure, each clip must typically be fastened to the wall panel and to the substructure, either directly or indirectly. This means that if an extremely high number of fasteners are used, it results in a great deal of time and effort spent in installation of the systems just to secure the clips to the panels prior to attaching the panels to the structure.
A number of different attachment systems have been introduced and employed in an attempt to overcome the challenges and alleviate the disadvantages discussed above. One known attachment system includes a plurality of locking members secured directly to, or formed integrally with, the outer surface of the return flanges of wall panels. The locking members secure the panel to a retaining member, which is itself secured to a surface of a building structure. The locking members are shaped such that they may be forced into a channel, but cannot be removed from that channel, such as angled surfaces with an apex adjacent the retaining member that resemble half of an arrowhead. The system may also optionally provide a drainage channel to carry water and other debris away from the surface of the building structure. While this attachment system allows for more efficient installation of an architectural wall panel system, it suffers from the disadvantage mentioned above relating to thermal cycling of the wall panel system because it does not allow for movement of the wall panels. In addition, the attachment system suffers from a number of new disadvantages, such as not providing adequate attachment strength to withstand some natural weather conditions, and making it extremely difficult to repair or replace installed wall panels as the locking members prevent the panel from being removed from the retaining members.
Other known attachment systems for securing wall panels of an architectural wall panel system to a building surface utilize some form of an insert wedged between the two adjacent flanges of adjacent wall panels, while the flanges are received in a channel. The insert is secured between the two flanges by a fastener, and fits snuggly therebetween to provide a seal against water and air infiltration. The insert may be made of an elastomeric material to allow for thermal expansion and contraction of the wall panels. This system, however, uses a high number of parts, and the thermal cycling of the system is limited by the small amount of movement allowed by the elastomeric insert. Furthermore, the elastomeric insert is subject to wear from the natural elements it will be exposed to, and subject to failure due to these elements and repeated expansion and contraction as a result of the thermal cycling of the wall panel system.
Additional attempts at improved attachment systems have included attachment systems utilizing variously shaped flanges extending along at least one edge of the wall panel to facilitate attachment of the panel to a building surface; attachment systems using rotatable retaining members secured to the mounting surface that rotate between a first (narrow) position designed to allow placement of the wall panels and a second (broad) position extending into slots in the wall panel flange to secure the panel in place, such as, for example, a T-shaped retaining member that rotates about an axis parallel to the wall panel flanges; and attachment systems having vents and filler strips which slide into grooves and are positioned within the gaps between adjacent wall panels to provide a watertight seal while allowing air flow therethrough. None of these attachment systems has proven noticeably advantageous over conventional attachment methods in providing a more efficient, reliable, and practical means of attaching architectural wall panels to the surface of a structure.
There is therefore a need for an improved architectural wall panel system, and specifically an improved attachment system for attaching architectural wall panels, that alleviates one or more of the disadvantages discussed herein.